Posted
by
timothy
on Monday May 26, 2014 @05:16AM
from the your-mileage-may-vary dept.

Taco Cowboy (5327) writes "Research carried out by UK consumer magazine What Car? which concluded that official manufacturers' MPG figures are unrealistic. Based on the research, new car buyers in the UK who trust official, government-sanctioned fuel economy figures will pay an average of £1,000 (€1,216) more than they expect on fuel over a three-year period. Since launching True MPG two years ago, What Car? has tested almost 400 cars in real-world conditions, using cutting-edge test equipment and achieving economy figures that are on average 19% lower than the government figures."

before making *any* judgement you *need* to watch the program on 5th gear which covers exactly this question in some detail. basically the test was designed originally for people driving sensibly, and it was designed i think well over 20 possibly even 30 years ago. so it has a very *very* gentle acceleration and deceleration curve. gentle acceleration because that is not only fuel-efficient but also the cars of that time simply could not accelerate that much, and gentle braking because again that is more fuel-efficient but also because if you had drum brakes they would overheat.

people no longer drive sensibly: they are more aggressive with other drivers (not keeping a safe distance), they put their foot down hard on the accelerator and they put their foot down hard on the brake. also as the cars are more reliable they tend to not maintain them properly: until i watched another program on 5th gear about how badly old oil affects fuel economy and the lifetime of the engine i had absolutely no intention of changing oil regularly in the decade-year-old cars i buy.

so, in effect, people should stop complaining and start driving in more fuel-efficient ways... *regardless* of how aggressive the person behind them gets when they set off from the lights at the same acceleration rate as a 40 tonne cargo lorry. that's the other person's problem.

That's all true, but manufacturers go to great lengths to inflate the figure.

I do wonder how someone so odiously dishonest as to participate in the practices you describe could ever become an engineer for a successful international brand.

Then, as someone who has been self-employed since 2003 and who has seen such a huge change in the way clients behave over the past decade, I wonder whether odious dishonesty today is a job requirement.

.... arn't the best solution. If they're so underpowered or peaky - like a lot of the new generation coming along - then people will tend to drive with their foot flat to the floor a lot mroe often which hammers fuel consumption and doesn't do the mechanicals any favours. Whereas with a bigger engine this is less of the case and you can get equivalent mpg except with a less stressed engine that isn't going to blow a seal after 75K miles because of components being worked to their limit to make up for the idiotically small capacity.

Of course left to their own devices no manufacturer would be dumb enough to put a 1.0L engine in a 1.5 ton car but EU regs now require silly emissions targets being met in these unrealistics tests so the manufacturers have no choice.

I'm a hypermiler. I get 51 mpg out of my diesel minivan, But I have to work really hard at it, drive slowly, draft trucks, avoid braking, coast and engine-brake whenever I can. It's so much work I usually can't drive with the radio on, to avoid distraction.

Fuelly [fuelly.com] shows the same model/year minivan routinely gets 35 mpg or less in normal driving condition. So it's almost entirely a matter of driving style rather than technical tricks.

Also set up wrong by the manufacturer. The 2007 honda civic has a highway MPG rating of 40mpg. I regularly get 44-46 while speeding after I fixed their design flaw in the rear end. they set the car with significant negative rear camber and with about 2 degrees of toe, I reset it to zero and zero and not only did fuel mileage numbers skyrocket by 10-15% but rear tire wear dropped to zero or undetectable. From what I can tell they STILL sell civics with this flaw, and the Honda Fit as well suffers from it.

Granted I only have about 10,000 miles of testing on this new adjustment, but there is no measurable tire wear on the rear and my wife has been driving it to work and back daily on a 45 mile commute as if she was in an indy car race trying to do 75-80mph. Gas mileage is measured two ways. 1st odometer+fuel used at the pump and a Scan Gauge I installed. they are within 1mpg of each other.

There is only one drawback to the change, the car is slightly more sensitive to steering input. I notice it, she does not. I am going to next add 2 degree of camber from the front to make it closer to zero as well as remove 2 degree of toe that may make the steering a bit too twitchy but you never know until you try. right now it has more than 8 degrees of camber and what looks like 9 degrees of toe. so the removal of that should further boost highway fuel economy but not as significantly as the rear end change. The rear was doing nothing but scrubbing the tires all the time, as most civic owners will tell you they have to replace the rear tires a lot as they start to cup, this is because of the dramatic flaw in how the rear end is set up on all 8th gen Civics.

Oh and I do these alignment changes in my garage, the "laser alignment" crap is nothing more than a scam. You can do a better alignment on your garage floor or driveway than the "experts" with the "highly advanced laser system" can.

Probably also driving too fast... European emission standards require testing at 90km/h, while the max speed in most EU countries is 120 or 130km/h

I'm in the U.S. and my car is rated 22mph city 29 mph highway. The city rating is dead on. The highway rating is off, I actually get 34 mph rather than the stated 29. My typical highway is designated 65 mph and when traffic is light it is practical to do 75 mph. At 75 mph I get 34. The rating of 29 may be based on obsolete 1970's 55 mph standards.

Maybe 55 was optimal with 1970's auto technology but it doesn't seem so today, at least for me. And of course YMMV is quite appropriate here.

Nothing you said has any bearing on advertised gas mileage. Nobody has patented gas mileage number calculations.

I'm guessing where you're going with this is the idea that without patents, everybody would design their cars identically to maximum gas efficiency, and we'd all know it was identical, and thus there would be no need to exaggerate. I think you'll find a lot of things besides patents that would do that, not least of which is borne out by the fact that companies put out multiple vehicles with multiple fuel efficiency ratings, despite having access to all the same tech.

A flaw it capitalism is that it resists its own proper functioning. For instance, ideal capitalism requires perfect information. Perfect information is always going to be unachievable, but as implemented capitalism doesn't even discourage people from working *against* perfect information, as they do by generating and propagating misleading gas mileage numbers.

An example more in your wheelhouse is that monopolies are the natural result of a successful organization in a market that contains barriers to entry, whether they are natural (like signal distribution eg. cable, fibre-optic, electrical) or artificial (patents, price dumping, product tying, buying up the entire raw materials market a la deBeers or Apple, etc.).

Those categories obviously tend to overlap with where we apply lots of regulation in practice.

Anyway, I'm guessing you think the root cause is that mileage-improving technologies are patented and thus unshared. I think you'll find that there are tradeoffs made even within a company.